The present invention relates generally to the manufacture of semiconductor integrated circuits (IC's), and particularly to the formation of field effect transistors (FETs) and, more particularly, to the formation of asymmetric halo implants in sub-45 nm technology FETs.
The current process for the formation of asymmetric devices in sub-45 nm technology ground rules is limited by shadowing and adjacency effects. Each asymmetric halo implant is shadowed by a block photoresist. An edge of the photoresist blocks the halo implant. Shadowing lowers the halo pocket doping concentration. This results in low threshold voltage and leaky transistor devices. Also, the electrical properties of asymmetric devices are perturbed due to the implantation steps necessary to enable adjacent devices. Each halo implant penetrates into the adjacent device.